Physical and chemical properties | Year 7 Chemistry (Cambridge) PDF Download

Introduction

• Properties of substances can be categorized into physical and chemical properties.
• Understanding these properties helps us describe and predict how substances behave.

Physical Properties

• Luster: Describes whether an object appears shiny or dull.
  • Example: Gold has a shiny luster.
• Hardness: Measures the ability of a substance to resist being scratched.
  • Example: Diamond is the hardest natural substance.
• Ductility: Ability of a substance to be drawn into wires.
  • Example: Copper is highly ductile.
• Malleability: Ability of a substance to be hammered or rolled into thin sheets.
  • Example: Aluminum foil is malleable.
• Conductivity: Ability of a substance to conduct heat or electricity.
  • Example: Copper is a good conductor of electricity.
• Density: Mass of a substance per unit volume.
  • Example: Lead is dense because it is heavy for its size.
• Solubility: Ability of a substance to dissolve in a solvent.
  • Example: Salt dissolves easily in water.
• Melting Point: Temperature at which a substance changes from solid to liquid.
  • Example: Ice melts at 0°C.
• Boiling Point: Temperature at which a substance changes from liquid to gas.
  • Example: Water boils at 100°C.

Chemical Properties

• Flammability: Ability of a substance to ignite and burn.
  • Example: Paper is flammable.
• Radioactivity: Ability of a substance to emit radiation.
  • Example: Uranium is radioactive.
• Oxidizing Ability: Ability of a substance to promote combustion.
  • Example: Hydrogen peroxide is an oxidizer.
• Corrosiveness: Ability of a substance to deteriorate or destroy other materials.
  • Example: Acid can corrode metal.
• Toxicity: Ability of a substance to harm living organisms.
  • Example: Mercury is toxic to humans.
• Explosiveness: Ability of a substance to explode under certain conditions.
  • Example: TNT is explosive.
• pH Level: Measure of acidity or basicity of a substance.
  • Example: Lemon juice is acidic, while soap is basic.

Conclusion

• Understanding physical and chemical properties helps scientists predict how substances will interact and behave in different situations.
• These properties are essential for various fields such as chemistry, materials science, and environmental science.